A hybrid vehicle may be propelled by an engine and an electric machine. In a situation where such a vehicle includes a high-performance vehicle with an electric machine downstream of a dual clutch transmission, there may be several issues associated with aggressive driving. In one example, during an upshift, when near a stability metric threshold, clutch pressures from the dual clutch transmission may create a speed change that creates an inertial torque disturbance that increases wheel torque, especially when the vehicle is turning. While such a disturbance may be reduced via the electric machine positioned downstream of the dual clutch transmission, via a motor positioned upstream of the engine, or via spark retard, reducing the disturbance in such a fashion may reduce longitudinal acceleration desired by a performance driver. In another example, as most operating conditions during aggressive driving, such as when racing, are either near the vehicle's stability metric threshold or near the powertrain's maximum power limits, such that there is little opportunity to charge a battery of the vehicle. Such circumstances may be encountered when turning or braking aggressively, such that the wheels are near the stability metric threshold, or under conditions where all vehicle power is requested to accelerate the vehicle.
The inventors have herein recognized the above-mentioned issues, and have developed systems and methods to at least partially address them. In one example, a driveline operating method comprises during an upshift of a transmission from a first gear to a second gear, adjusting a clutch pressure of the transmission to adjust slippage of a clutch in response to a vehicle stability control parameter exceeding a threshold.
In an example of such a method, the method may further comprise adjusting slippage of the clutch in further response to battery state of charge, and may further comprise adjusting engine toque via spark timing in response to the vehicle stability control parameter exceeding the threshold.
In another example, a driveline operating method comprises during an upshift of a transmission from a first gear to a second gear, adjusting an amount of driveline torque absorbed via an electric machine during an inertia phase of the upshift in response to a vehicle stability control parameter.
In still another example, a driveline operating method comprises adjusting clutch pressure of a transmission clutch during an upshift in response to a vehicle stability control parameter such that torque delivered to wheels of a vehicle via a driveline does not cause the vehicle stability control parameter to exceed a vehicle stability control threshold.
In this way, the possibility of decreasing vehicle stability may be decreased via increasing upshift duration, increasing engine spark retard, increasing torque absorbed from a driveline via an electric machine, and/or increased transmission clutch slip. Increasing the shift duration reduces torque delivered to the transmission output shaft as does reducing engine torque via spark retard. The reduced transmission output torque may provide additional vehicle stability. Further, vehicle stability may be improved via reducing wheel torque by absorbing transmission output torque via an electric machine positioned downstream of the transmission.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.